ABS resins are widely used for the production of automobiles, household electrical appliances, OA equipments or the like due to its superior mechanical properties, heat resistance and moldability.
However, when components of the ABS resin or said component and other components of other materials are used to come into contact with and rub against each other, squeaking noises (rubbing noises) may be generated. For example, when the contacting component of the ABS resin is used as automobile interior components, with vibration during car driving, the interior components or the interior component and other members such as living sheet or foam made of a polyvinyl chloride, a chloroprene rubber, a polyurethane, a natural rubber, a polyester or a polyethylene come into contact with and rub against each other, squeaking noises (rubbing noises) may be generated. For example, in a ventilator made of the ABS resin is installed a valve shutter using a chloroprene rubber foam or the like as a sealing material in order to adjust an air quantity. If the valve shutter is rotated for air quantity adjustment, a case of the ventilator rubs against the sealing material as another member, so that squeaking noises may be generated. The squeaking noises is known as a noise risk caused by a stick slip phenomenon generated when two objects rub against each other. The stick slip phenomenon is different from slidability of resins and has an independent property.
Since the styrene resins such as the ABS resin are amorphous resins, they are higher in coefficient of friction as compared with crystalline resins such as a polyethylene, a polypropylene and a polyacetal, and it is well known that, like a switch component of an instrument panel in an automobile or a sliding component of a business desk, when used to fit with another member, a stick slip phenomenon as illustrated in FIG. 1 occurs to generate unpleasant sounds (squeaking noises). The stick slip phenomenon is a phenomenon that is generated when two objects rub against each other. As illustrated by a model of FIG. 2(a), when an object M connected with a spring is placed on a driving table that moves at a driving speed V, the object M moves toward the right direction first as illustrated in FIG. 2(b) together with the table moving at the driving speed V by the action of a static frictional force. When the force by which the object M is to be restored to its original position becomes equal to the static frictional force, the object M starts to slip in the opposite direction to the driving speed V. At this time, the object M comes to receive a kinematic frictional force, and the slip is stopped when the force of the spring becomes equal to the kinematic frictional force as illustrated in FIG. 2(c), so that the object M comes again into a state where it attaches on the driving table and it moves again in the same direction as the driving speed V (FIG. 2(d)). This is called a stick slip phenomenon. As illustrated in FIG. 1, it has been said that if the difference Δμ between the coefficient of static friction μs and the coefficient of friction μl of the lower end of a saw wavy form is large, squeaking noises tend to be generated easily. A dynamic friction coefficient is a middle value between μs and μl. Therefore, even when the absolute value of the coefficient of static friction is small, squeaking noises tend to be generated if Δμ is large.
Those squeaking noises are a major cause that spoils comfortableness and silence in rooms of automobiles, offices and houses, and therefore reduction of squeaking noises is demanded strongly.
In order to solve the above-mentioned problems, it is known that an automobile interior component made from a thermoplastic resin composition obtained by blending the specific silicone oil with the specific rubber-modified vinyl resin is reduced remarkably in squeaking noises and the effects of reducing the squeaking noises are maintained even when placed at high temperatures for a long time, and further is superior in impact resistance (Patent document 1).
On the other hand, a component of an ABS resin is used as an automobile interior component, for example, a driver is often dazzled by sunlight reflected at the surface of the molded article, a measuring instrument is difficult to be watched by reflected light in the vicinity of the measuring instrument, or the like, and therefore, appearance superior in matting property is demanded from the viewpoint of safety. Moreover, in a housing, a chassis and the like of household electrical appliances, OA equipments and the like, appearance superior in matting property is demanded from the viewpoint of design.
It is known that a thermoplastic resin composition superior in matting property, impact resistance, heat resistance, dimensional stability and moldability and a molded article by an injection molding of this resin composition are obtained by blending the specific resin composition containing a crosslinked copolymer rubber with the resin composition comprising a polycarbonate resin or a polycarbonate resin and an ABS resin. (Patent document 2).
However, it is a real situation that a resin composition providing a molded article which is not only reduced in squeaking noises even when placed under high temperatures for a long time, but also superior in appearance in matting property has not yet been obtained.